Digital data may be stored on flexible or "floppy" disks or on hard or Winchester-type disks by the magnetization of successive small areas on the magnetic surface of the disk by a magnetic head or slider as the disk rotates. The density of digital storage on hard disk memory systems is in the order of ten or twenty times the density achieved with floppy disk memory systems. Concerning the use of the terms "magnetic head" or "slider", the terms are used herein somewhat interchangeably, but with "slider" being used primarily to designate the monolithic or composite member per se, and the term "magnetic head" or "magnetic head assembly" referring to the slider and some portion of its associated suspension.
In the field of Winchester-type disks, the early systems involved a linear movement of the heads or sliders radially to the center of the disks; and certain standard magnetic heads or sliders and their suspensions were developed with a mounting slot on the side of the slider away from active side of the slider which faces the rotating disk; and the longitudinal axis of the slider was oriented perpendicular to the longitudinal axis of the suspension in order to maximize performance in a linear head positioner. Incidentally, because of the high speed of rotation of the rigid disks, the heads or sliders usually "fly" a few millionths of an inch above the surface of the disk. The mounting slot was transverse to the longitudinal axis of the slider and extended radially with respect to the disks for sliders of the low cost "monolithic" type of "composite" type.
Rigid or Winchester-type magnetic storage disks were originlly relatively large in diameter, but in the last few years the size has been reduced, so that five and one-quarter inch disk systems are now widely available. As disk drives shrank in size, rotary had positioners became attractive from a cost and space viewpoint.
In order to adapt the reliable available heads or sliders for use with 51/4 inch disk rotary positioner systems, it was simple to mount the linear slider suspensions perpendicular to and on the end of a pivotal arm, to form a "right angle" configuration, with the slider and its adjacent "load beam" mounting member moving substantially as before along a shallow arc across the disk rather than with a purely linear motion along a radial line. The longitudinal axis of the slider was also at right angles to the adjacent "load beam" mounting member. While this right-angle or "dog-leg" arrangement simplified the original design effort for rotary head positioner systems, the weight and inertia of the right angle style mounting arms were excessive, in view of the need to shift the head rapidly across the surface of the disk to access new information.
In order to reduce the weight and the moment of inertia of the head mounting arms, straight pivoted arms were then developed with the support arm, or suspension, aligned with and overlying the slider. However, with conventional monolithic sliders, this forms a relatively thick assembly so that the spacing of the disks in multiple disk units is greater than would be desirable (due to fact that each disk surface usually has a head-suspension assembly interfacing to it), and the resultant digital storage density is not as high as would be desirable due to a reduction in the total number of disks.
Accordingly, principal objects of the present invention are to reduce the inter-disk spacing, and increase the total storage of multiple hard disk storage systems, using a slider suspension having a relatively low moment of inertia, so that the heads may be moved across the disk at high speeds and with a relatively lightweight, low-power, actuator.